滇西北亚高山针叶林林窗大小与更新的初步分析

EFFECTS OF GAP SIZE ON REGENERATION OF SUBALPINE CONIFEROUS FORESTS IN NORTHWEST YUNNAN

分析了云南西北部碧塔海自然保护区的亚高山针叶林林窗大小对林窗植被和更新的影响 .调查区域出现I级林窗 (面积 <5 0m2 )占 36 % ,II级 (5 0～ 75m2 ) 2 1% ,III级 (75～ 10 0m2 ) 19% ,IV级 (10 0～ 12 5m2 ) 13%和V级 (>12 5m2 ) 11% .结果表明 ,亚高山针叶林因林窗大小不同而导致小环境条件的差异 ,使林窗植被和更新与林窗干扰密切相关 .林窗大小对林窗植被的物种多样性、结构、密度分布以及云冷杉更新苗的空间分布都有不同程度的影响 .小林窗(I级 )的物种多样性比大林窗 (IV级和V级 )、中林窗 (II级和III级 )高 .云冷杉更新幼苗以中、小林窗较多 ,且在小林窗中呈随机分布 ,主要分布在林窗中心和过渡区域 (88% ) ;在大、中林窗中则呈集群分布 ,主要分布在过渡区域 ,占4 4 %～ 5 0 % .同时 ,研究表明该区亚高山针叶林有效更新的林窗阈值面积大约为 75m2 .图 4表 3参 2

Effects of gap size on regeneration of subalpine coniferous forests in northwest Yunnan, and species diversity, structure, distribution of the gap vegetation were analyzed. There were 36% of class I (gap area <50 m 2 ), 21% of class II (50～75 m 2 ), 19% of class III (75～100 m 2 ), 13% of class IV(100～125 m 2 ) and 11% of class V (>125 m 2 ) forest gaps. The results showed that there was the maximum of species diversity index, a lot of seedlings of Picea spp. and Abies spp. and random distribution in small gap (class I gap), and clump of the seedlings to middle (class II and III gaps) and large (class IV and V gaps) ones. Further, many seedlings distributed in central and intermediate zones (88%) in small gaps, and in intermediate zone in middle (47%) and large (50%) ones. The results also suggested that the seedlings of Picea spp. and Abies spp. adapt to shade environment, and the threshold gap size keeping on regeneration may be about 75 m 2 in the subalpine coniferous forests. Fig 4, Tab 3, Ref 22